1. Field of the Invention
This invention concerns fire escape devices for use in lowering persons from high-rise buildings. More particularly, it concerns fire escape devices using fluid pumps which avoid dependence on electrical power.
2. Discussion of the Background of the Invention
The prior art has severe problems in dealing with three major characteristics of emergency escape situations from high-rise buildings.
The first is that emergency events requiring evacuation, such as fire, earthquake or sudden structural failure, usually causes an interruption in the supply of utilities such as electrical power.
The second major problem in such an emergency situation is that the people who must be evacuated cannot be assumed to be in any particular physical condition or have any specified qualifications. A practical escape apparatus must allow for people who have limited strength, are handicapped, or who are relatively immobile.
Additionally, an evacuation emergency will induce panic, making it more difficult for persons being evacuated to perform complex tasks. A simple, straightforward escape device is required to meet the needs of persons in a panic situation.
Elevators have been excluded as an escape apparatus both because of their known propensity to be damaged by the loss of electrical power and because their control will fail catastrophically during a fire. They are so dangerous that they are posted with signs according to standard safety regulations prohibiting their use during such an emergency.
Evacuations normally involve one of three techniques. The first and oldest technique is individual descent from the building by use of various forms of escape ladders or stairs. It should be obvious that in a high-rise building, defined as one having more than approximately eight to ten stories, a significant number of the people will lack the strength to descend such a ladder, and panic will result in piling up of people, falls, and serious injury during the long descent. Fire escape stairs, integrally built into a high-rise building, are additionally notorious during a fire where many people lose their lives. In addition, persons who are handicapped simply cannot use such an escape means.
The second technique is removal by external escape devices. Ground based devices are all functionally "cherry picker"-like assemblies which can be raised from the ground, but which are ultimately limited to about the first four to five floors of any building. This renders them useless in the case of a high-rise escape situation. Helicopter escape is impractical except for removing people from the flat roof of a building while turbulence encountered in a fire situation often renders the operation of a helicopter in close proximity to a burning building extremely risky.
The third technique involves a single person brake and descent device. As shown by U.S. Pat. No. 3,844,377 or U.S. Pat. No. 2,873,055, these devices comprise individual escape harnesses suspended from a cable which is paid out from a brake mechanism.
The '055 patent shows a friction brake. Such a mechanism is affected by the fact that, as standing friction exceeds sliding friction, it tends to lock up. Thus there must be a controlled means to release the brake to start descent; thereafter controlled descent depends both on the continued maintenance of a minimum sliding friction and the lack of failure in the controller. Since, by design, the controller must be capable of releasing braking force, there is always the chance that the apparatus will fail, releasing the brake and dropping the evacuee to his doom.
The '377 patent shows a powered descent device which requires a driving means and a power source. This apparatus employs an electric motor and a battery. Such devices require constant maintenance, must be isolated from building utility services due to the high probability of failure during an emergency, and are prone to failure, trapping victims and preventing escape.
U.S. Pat. No. 4,018,423 issued to Belew avoids the friction braking problem by using a vane rotating in a closed fluid cylinder. While this disclosure avoids the runaway problem of friction brakes, it is essentially a torque converter that developes torque as a function of rotational velocity. Increasing the descent load of such a device increases the velocity of descent. Such an apparatus is, by design, restricted to a single optimum weight load.
It is an object of the present invention to overcome these constraints of the prior art and provide a more realistic escape apparatus.
First, since the occupancy of a high-rise building is variable, unpredictable, and often high, it is an object of this invention to provide an escape apparatus which will provide a uniformly controlled emergency descent under widely varying conditions of load.
It is a second object of this invention to provide an apparatus which can be used safely by people during a panic situation, without requiring physical skill or strength on the part of the user and without requiring the mastery of a complex operational process.
It is another object to provide an escape apparatus that will remain functional during prolonged storage with limited maintenance. This invention will, in fact, continue to function reliably in the event of no maintenance. It is thus an important aspect of this device that it does not require the presence of any utility services from the building, nor does it require skill, knowledge, or training on the part of the users, and it will continue to function reliably even after an extended period in storage.